Summary of Weighted Average Grant-Date Fair Values And Weighted Average Assumptions Used to Calculate Fair Value of Options Granted (Detail) - Stock Options - $ / shares	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Valuation assumptions:
Weighted average grant-date fair value	$ 29.57	$ 9.29	$ 9.85
Risk-free interest rate	1.55%	1.60%	0.94%
Expected option life (years)	4 years 1 month 24 days	4 years 2 months 9 days	4 years 3 months
Expected volatility	49.70%	49.30%	51.70%